The present invention relates generally to the field of medical devices and, more particularly, to devices and methods for removing objects from within a body passageway, such as a blood vessel.
Cardiovascular disease, including coronary thrombosis, is the leading cause of death in the United States. It has been estimated that at least 280,000 cases of pulmonary emboli occur annually in the United States, with slightly less than 50% mortality. Streptokinase has gained popularity in the treatment of pulmonary embolism and thrombophlebitis, most recently being used for occluded grafts and thrombosis associated with atherosclerotic disease (coronary arteries and extremities). In these situations, prompt removal is critical, since a delay in restoration of flow results in irreparable tissue damage. Unfortunately, several hours of streptokinase infusion may be required to remove large clots. Thus, this procedure is too often ineffective.
Greenfield et al. have developed a method for percutaneous clot removal using a cup-like device attached to a steerable catheter. This method is disclosed in the following articles: L. J. Greenfield et al., Transvenous Management of Pulmonary Embolic Disease, Ann. Surg., 180:461-468 (1974); L. J. Greenfield et al., Hemodynamic and Respiratory Responses to Transvenous Pulmonary Embolectomy, J. Thorac. Cardiovasc. Surg., 62:890-897 (1971). As the clot is sucked into the cup, the catheter is retracted. In most cases, the disadvantageous size of the system and the possibility of dislodging the clot from the cup during retrieval make this method less than satisfactory.
The use of a non-tapered catheter inserted into a vessel through a sheath to remove thrombi from peripheral vessels by transcatheter aspiration is known, such being most recently described in the following article: K. W. Sniderman et al., Percutaneous embolectomy by transcatheter aspiration, Radiology, 150:357-361 (1984). Unfortunately, such catheters exhibit problems when the thrombus is too large to be aspirated within the catheter lumen, therefore requiring an active method of fragmentation and transport.
An active method of fragmentation and transport of a thrombus within a catheter tube is described in T. Akimoto, Coronary Artery Thrombus Extirpation Catheter, Bulletin of the Heart Institute, Japan, pages 49-58 (1969). The apparatus and method disclosed therein involved the use of a spiral wire rotatably driven within a polyethylene catheter tube. Rotation of the spiral wire within the tube facilitated transcatheter transportation of the thrombus by screw movement. A blunt ring on the tip of the spiral wire extended outside the catheter in order to destroy the thrombus. Unfortunately, this apparatus was abandoned since in dog coronary arteries the loop perforated the arteries frequently.